1. Field of the Invention
This invention relates to apparatus, methods, and systems for purifying, and maintaining the purity of, water supplies, and in particular potable water supplies, on transportation equipment, such as planes, trains, ships, and the like. The invention further relates to two aspects: the first aspect concerns apparatus, methods, and systems for purifying water supplies as they are loaded into the transportation equipment, to ensure that the water is supplied in initially purified, desirably potable, form; the second aspect concerns apparatus, methods, and systems for treating the water while the transportation equipment is in operation, maintaining the purified nature of the water for the duration of a trip.
2. Description of Related Art
The issue of water quality, and in particular, of potable water quality, on transportation equipment, such as aircraft, trains, boats and ships, and the like is becoming more of a concern to regulatory authorities. This is particularly true in the United States for commercial passenger airlines with respect to the potable water supplies contained aboard commercial aircraft.
According to the U.S. Environmental Protection Agency (“EPA” or “Agency”), more than twelve percent of passenger aircraft tested in the United States during August and September 2004 “carried water that did not meet EPA standards.” Water on-board these aircraft tested positive for total coliform bacteria, with some water also testing positive for E. coli bacteria. As noted by the EPA, “[b]oth total coliform and E. coli are indicators that other disease-causing organisms (pathogens) could be in the water and could potentially affect people's health.” See “Airline Water Supplies” at http://www.epa.gov/airlinewater.
On Nov. 9, 2004, EPA announced commitments from numerous U.S. passenger airlines “to implement new aircraft water testing and disinfection protocols.” Administrative agreements executed with these airlines require increased monitoring of water quality on-board commercial aircraft. They also require airlines to analyze possible sources of contamination existing outside their aircraft and “to provide information related to practices of boarding water from foreign public water supplies not regulated by EPA.” See “EPA Reaches Agreement with Major Airlines to Implement New Aircraft Water Protocols” at http://yosemite.epa.gov/opa.
Clear from EPA's recent public announcements is that improving water quality on-board passenger aircraft is an important objective of the Agency. Systems and techniques effecting such improvement thus may provide valuable tools to U.S. airlines as they seek to comply with the administrative agreements. They may also be useful to the EPA as it works to enhance the quality of drinking and other water made available to the public.
U.S. Pat. No. 4,871,452 to Kohler, et al., entitled “On-Board Water Supply,” discloses equipment for purifying waste water from galleys, sinks, and toilets of aircraft. Waste water from these areas discharges to a tank, after which it passes through a mechanical filter, a bed of active carbon, ozone and osmotic stages, and a disinfection stage involving addition of chlorine and irradiation with ultraviolet (“UV”) light. Thereafter, the water is made available to aircraft passengers for certain uses.
Discussed in U.S. Pat. No. 6,143,185 to Tracy, et al. are alternate systems for decontaminating waste water from aircraft toilets, sinks, and galleys. They too include a mechanical particulate filter, activated carbon, and a source of UV light. Alternatively, according to the Tracy patent, the waste water may be exposed to microwaves or treated with chlorine or iodine. A sensor may be used to measure “the level of clarity of the treated water as an indication of its purity” and restrict opening of a control valve until acceptable clarity levels are obtained. The entire contents of both the Kohler and Tracy patents are incorporated herein by this reference.
However, these systems and methods are directed at purifying wastewater removed from the aircraft. Currently, airlines typically attempt to ensure that the potable water aboard the airplanes is fit for human consumption by employing a quarterly disinfection protocol and monthly water sampling. In addition to being time consuming and labor intensive, these techniques may not be sufficient to satisfy the EPA under the agreements described above.
Moreover, quarterly disinfection does not adequately address the issue of contamination introduced in uploaded water, which is of particular concern for aircraft flying to and from, and being serviced in, non-industrialized areas. In addition, air must be introduced into the water storage and dispensing system on the aircraft in order to maintain pressurization, as well as to drain the system during routine servicing. This air can introduce pathogens that can multiply, and cause unsanitary conditions and unacceptable water quality in the intervals between samplings or disinfection procedures. In effect, because the water storage and dispensing system is routinely exposed to the outside environment, potable water quality cannot be ensured without some form of continuous treatment.
Continuous treatment of potable water supplies presents another set of potential problems to be solved, however. Continuous treatment requires continuous or semi-continuous dosing of the water, with the requisite dosing equipment (metering and monitoring equipment, dosing agent storage equipment, and/or equipment for in-situ generation of the dosing agent). Conventional dosing of sanitizing chemicals often requires continuous, real-time monitoring is also necessary to ensure adequate performance.
As a result, there remains a need in the art for an apparatus, method, and system for continuous treatment of portable water supplies to purify, or maintain the purity of the water supplies, that does not require continuous real-time monitoring, that is essentially self-regulating, and that is easily transportable (e.g., on aircraft), without the need for large or heavy dosing or monitoring equipment.
In addition, in order to reduce the load on such a purification system, and to provide purified water for transportation equipment without such a purification system, there remains a need in the art for apparatus, methods, and systems capable of purifying water before it is uploaded to the transportation equipment.